Most archaeological sites have been located by means of careful searching, while many others have been discovered by accident. Olduvai Gorge, fell into its deep valley in 1911.Thousands of Aztec artifacts came to light during the digging of the Mexico City subway in the 1970s.Most archaeological sites , however , are discovered by archaeologists who have set out to look for them. Such searches can take years.
通过仔细搜索：by means of careful searching
恰好掉入深谷：literally fall into the deep valley
重见光明：come to light
开始做某事：set out to do something
Olduvai Gorge , an early hominid site in Tanzania , was found by a butterfly hunter who literally into its deep valley in 1911.
However,manyleadingAmerican universities want their undergraduates to have a grounding in the basic canon of ideas that every educated person should posses. But most find it difficult to agree on what a“general education”should look like.At Harvard，Mr Menand notes，“the great books are read because they have been read”--they form a sort of social glue.One reason why it is hard to design and teach such courses is that they can cut across the insistence by top American universities that liberal-arts education and professional education should be kept separate , taught in different schools .